Photomerge Contrast Problem in CC 2014

Photomerge seems to be introducing large amounts of contrast in the CC 2014 (15.1.0) version. Here is an infrared pano (only edit is cropping). Note that the histogram is blocking-up in the shadows and that highlights have been pushed almost to blowing-out.

Meanwhile, the same source files run through CC (14.2.1) with the same settings are fine.

I've searched for Photomerge issues in CC 2014 and am aware there is a known problem. It's unclear to me whether contrast gain is being addressed, though.